"The US military would most likely use Tomahawk cruise missiles for an attack on the Syrian government forces. These missiles are now stored on destroyers in the eastern Mediterranean.

"The missiles would not be fired at places where chemical weapons might be stored, since poisonous gas could spread or chemical agents could fall into the wrong hands.

"Instead, military facilities would be targeted — radio centres, command posts and missile launchers, says Douglas Ollivant, who served as an operations officer with the Army's Fifth Cavalry Regiment in Iraq.

The 'do little option' of "launching a symbolic strike, destroying a few arms depots and runways" that is accompanied by "strident warnings" from American officials saying "that if chemical weapons were ever used again, there would be greater punishment next time."

The 'do a little more' option: "Rebels would certainly be encouraged by strong U.S. military strikes, especially if they carry on through two to three days. The strikes could help the rebels advance."

"But they could also create a false optimism, a belief that the regime is collapsing when in fact it is not."

Or the 'do a lot' option of attacking military targets in Syria "in a major way" – an option that seems to be predicated on the type of international cooperation that seems to be lacking after the British Parliament rejected London.

"It's still not clear what positive objectives a limited use of force would accomplish. It won't tip the balance inside Syria or drive Bashar al-Assad from power. It's not even clear that punitive strikes would do much to reinforce the norm against chemical weapons use, as any leader contemplating the use of these weapons in the future is probably going to be in pretty dire straits and might not care if some foreign power might retaliate. Moreover, the American people are clearly not interested in getting into this war, and Obama and the Dems could pay a big price if retaliation goes awry in any way."